Apparatus for the fixing of the position of bone cuts

ABSTRACT

The invention relates to an apparatus for the fixing of the position of bone cuts for the insertion of knee implants comprising at least one cutting template which can be coupled to a base element fixed to the bone in the region of a condyle and can be fixed to the base element, wherein the cutting jig defines, in the fixed state and in each case by means of a slot for a cutting tool, a first cutting plane with respect to the base element and a second cutting plane with respect to the first cutting plane, and wherein the orientation of the second cutting plane can be set relative to the first cutting plane when the cutting jig is coupled to the base part and the respect knee anatomy is taken into account.

[0001] The invention relates to an apparatus for the fixing of theposition of bone cuts for the insertion of knee implants.

[0002] When knee prostheses are inserted, the condyles of the tibia andof the femur must be prepared in order to create contact surfaces on thebone which ensure a defined position of the tibia and femur implants.

[0003] The contact surfaces are produced by cutting away bone materialat the condyles. In this process, one endeavors to remove as little bonematerial as possible. Furthermore, care must be taken that the cutsurfaces at the tibia and at the femur are correctly oriented relativeto one another so that the tibia and femur implants can cooperate in amanner corresponding to the natural movement of the knee joint.

[0004] This is in particular difficult in uni-compartmental operationsin which a knee prosthesis should be implanted either only in the medialcompartment or only in the lateral compartment. No instruments haveexisted to date with which the bone cuts to be carried out for thispurpose can be fixed with the desired accuracy both with respect totheir position and orientation relative to the respective condyle andwith respect to the cut depth, above all in the direction oflateral-medial.

[0005] It is the object of the invention to provide an apparatus of theinitially named kind with which the position of bone cuts to be carriedout on the respective condyle can be fixed in as simple and as reliablea manner as possible and with an accuracy which is as high as possible,wherein this should in particular take place while taking the respectiveanatomic relationships into account as much as possible.

[0006] This object is satisfied by the features of claim 1 and inparticular in that the apparatus includes at least one cutting jig whichcan be coupled to a base element fixed to the bone in the region of acondyle and which can be fixed to the base element, with the cutting jigin the fixed state respectively defining —by means of a slot for acutting tool —a first cutting plane with respect to the base element anda second cutting plane with respect to the first cutting plane, and withthe orientation of the second cutting plane being adjustable relative tothe first cutting plane, when the cutting jig is coupled to the baseelement and taking the respective knee anatomy into account.

[0007] The apparatus for the fixing of the position of bone cuts inaccordance with the invention is preferably made for the fixing of theposition of bone cuts on a tibial condyle as part of a uni-compartmentalknee operation by which a tibia plateau is produced which is preferablydefined by two cutting surfaces extending perpendicular to one anotherand onto which a tibia implant of the knee prosthesis can be mounted inthe further course of the operation.

[0008] In the following, in the further explanation of the invention,reference is made only to its use in conjunction with a tibial condylefor the simplification of the representation.

[0009] The invention starts from a basis element which is fixedcorrectly with respect to the position and orientation in the region ofa condyle to be treated and which only defines a plane, without the cutdepth being defined in any direction in the plane or parallel to theplane.

[0010] A reference is available with this base element relative to whichthe first cutting plane is fixed by means of the set of instruments inaccordance with the invention. It is possible in accordance with theinvention to define a second cutting plane relative to said firstcutting plane and to set the orientation of said cutting plane relativeto the first cutting plane. This can take place in accordance with theinvention while taking the respective knee anatomy into account.Consequently, the invention not only permits two cutting planes to befixed directly with respect to the basis element and relative to oneanother, but moreover to take the anatomical circumstances of therespective knee into account in this process.

[0011] Preferred embodiments of the invention are recited in thedependent claims, in the description and in the drawing.

[0012] Provision is preferably made for the first cutting plane and thesecond cutting plane to extend perpendicular to one another.

[0013] Provision can furthermore be made in accordance with theinvention for the orientation of the second cutting lane to beadjustable with the cutting jig movable relative to the base element.The cutting jig can hereby be moved relative to the base element andsimultaneously the orientation of the second cutting plane changed,whereby the slots formed at the cutting jig can be ideally aligned inaccordance with the respective anatomical circumstances of the kneebefore the cutting jig is fixed to the base element.

[0014] The cutting jig is preferably only movable parallel to the firstcutting plane in the state still not fixed. The position and theorientation of the first cutting plane relative to the base elementhereby do not change on the movement of the cutting jig relative to thebase element. Provision can furthermore be made for the cutting jig tobe movable only in a straight line relative to the base element. Forthis purpose, a guide groove can be formed at the base element by whichthe cutting jig is compulsorily guided at the base element.

[0015] In accordance with a further embodiment of the invention, it isproposed that the cutting jig has at least one guide for an abutmentelement which, in at least one of the cutting planes, forms an abutmentfor the cutting tool restricting the respective cut.

[0016] The cutting depth can hereby be bounded in the correspondingdirection in a simple and secure manner such that unwanted damage to thebone is avoided. The surgeon can concentrate on the carrying out of thecut and does not need to keep an eye on the cutting depth since he canrely on the correctly positioned abutment element in this respect.

[0017] The guide for the abutment element can be made such that theabutment element lies on the line of intersection of the two cuttingplanes. The desired line of intersection of the two cutting planes canhereby be precisely fixed by means of the abutment element. In thisprocess, a boundary is fixed for both cutting planes with only onesingle abutment element.

[0018] Provision can furthermore be made in accordance with theinvention for the guide for the abutment element to be forcibly coupledto the slot defining the second cutting plane. When setting theorientation of the second cutting plane, the orientation of the abutmentelement is hereby simultaneously fixed, whereby the handling of theinstrument in accordance with the invention is further simplified.

[0019] The guide can include a passage which is formed in the cuttingjig and through which the abutment element can be inserted. This passagecan simultaneously serve as a guide for a drill with which the bone isfirst predrilled in order to subsequently be able to insert the abutmentelement into the bone.

[0020] In a preferred embodiment of the invention, an adjustable probedevice is provided to take the knee anatomy into account and can becompulsorily coupled to the slot of the cutting jig defining the secondcutting plane, with it being possible to set a plurality ofpredetermined implant sizes by adjusting a probe relative to a base partcoupled to the slot.

[0021] A coupling section can be provided for the coupling to the slotand the probe device can probe the position of the eminentia and of thecruciate ligament anchoring via the former in order to make the slotdefining the second cutting plane fixable with a safety spacing.

[0022] The orientation of the second cutting plane can be set using sucha probe device in dependence on the anatomical circumstances of therespective knee. The surgeon can determine the implant size best suitedfor the operation by changing the orientation of the second cuttingplane with a simultaneous adjustment of the probe relative to the basepart coupled to the slot.

[0023] Provision is in particular made in accordance with the inventionfor the slot defining the first cutting plane to be formed by anintermediate space present between the upper side of the base elementand a side of the cutting jig facing the base element when the cuttingjig is coupled to the base element. When making the first cut, thecutting tool is consequently guided between the base element and thecutting jig. The cutting tool can lie on the upper side of the baseelement in this process. A displacement of the cutting jig relative tothe base element does not change anything in the orientation and in theposition of the slot defining the first cutting plane.

[0024] In a further embodiment of the invention, provision is made forthe cutting jig to include a turntable arrangement with a turntablewhich is rotatably supported at the cutting jig and with which a guidesection is rotatably fixedly connected in which the slot defining thesecond cutting plane is formed. The rotational axis of the turntable canextend perpendicular to the first cutting plane in this process.

[0025] Provision can furthermore be made for a further guide section tobe rotatably connected to the turntable and to be formed as a guide forthe abutment element. The relative position between the slot definingthe second cutting plane and the guide for the abutment element canhereby be fixedly pre-determined in a simple manner.

[0026] The cutting jig can furthermore have a clamping device with anactuating member by means of which the cutting jig can be fixed relativeto the base element and simultaneously the orientation of the secondcutting plane can be fixed relative to the first cutting plane. Thecutting jig in accordance with the invention can so-to-say hereby befixed in the desired position simultaneously with a single motion withrespect to all degrees of freedom of movement provided for the fixing ofthe position of the bone cuts.

[0027] The cutting jig can include a base part made in a U shape andbeing able to be pushed onto the base element with U limbs extendingparallel to the first cutting plane, a clamping lever pivotablysupported at the base part about an axis which extends parallel to thefirst cutting plane and perpendicular to the U limbs of the base partand a clamping spindle extending parallel to the U limbs of the basepart and cooperating with the clamping lever via a thread, with aturntable arrangement rotatably supported at the upper U limb of thebase part about an axis extending perpendicular to the first cuttingplane and having the slot defining the second cutting plane beingcapable of being fixed by a rotational actuation of the clamping spindleand simultaneously the clamping lever being pivotable relative to thebase part into clamping engagement with the base element.

[0028] In this process, a free end region of the clamping spindle can bemade for the fixing of the turntable arrangement and can be brought intoclamping engagement with an outer rim region of the turntablearrangement by rotational actuation of the clamping spindle.

[0029] Furthermore, the clamping lever can include an actuation arm anda clamping arm, with the clamping spindle cooperating with the actuatingarm and the clamping arm being pivotable, for the clamping tight of thebase element located between the two U limbs of the base part, byrotational actuation of the clamping spindle via the actuating arm intothe region between the two U limbs and toward the base element.

[0030] An accidental release of the clamping engagement, for example dueto vibrations occurring during the carrying out of the bone cuts, can beprevented in a particularly reliable manner if, in accordance with afurther embodiment of the invention, cooperating thread sections of theclamping spindle and of the clamping lever are held free of clearance bya spring tensioned between a contact section fixed relative to thespindle and the actuation arm of the clamping lever.

[0031] The intermediate space between the two U limbs of the base partis preferably matched to the height of the base element.

[0032] The invention permits the use of comparatively thin base elementswhich, for example, have a thickness of only approximately 12 mm.

[0033] The invention will be described in the following by way ofexample with reference to the drawing. There are shown:

[0034] FIGS. 1 to 5 different phases of part of a knee operation inwhich bone cuts are carried out on a tibial condyle by means of anapparatus in accordance with the invention;

[0035]FIG. 6 different views of a cutting jig in accordance with anembodiment of the invention;

[0036]FIG. 7 different views of a probe device in accordance with anembodiment of the invention which can be used with the cutting jig ofFIG. 6; and

[0037]FIG. 8 different views of an abutment element in accordance withan embodiment of the invention which can be used with the cutting jig ofFIG. 6.

[0038] Before constructive details of the apparatus in accordance withthe invention are considered with reference to FIGS. 6 to 8, that partof a knee operation should be explained with reference to FIGS. 1 to 5in which the apparatus in accordance with the invention is used.

[0039] It is the aim of the total operation to insert a knee prosthesisconsisting of a tibia implant and a femur implant. Uni-compartmentalsurgical procedures are above all of interest in connection with theinvention by which initially a plateau is created at the respectivetibial condyle by cutting away bone material for the tibia implant to beinserted, whereupon the opposite femoral condyle is likewise preparedfor the fixing of a corresponding femur implant by cutting away bonematerial.

[0040] In this process, not only a correct positioning of the tibiaimplant at the tibia and of the femur implant at the femur is important,but also and quite decisively the correct alignment of the tibia implantand of the femur implant relative to one another. To ensure the correctpositioning of the implants, in addition to a good surgical plan, anexact carrying out of the bone cuts required to remove the bone materialis of decisive importance.

[0041] The present invention relates, in accordance with the embodimentshown in the Figures, to the fixing of the position of bone cuts to becarried out on a tibial condyle for the producing of a plateau for atibia implant by means of a set of instruments which permits the cuttingplanes to be fixed while taking into account the anatomicalcircumstances of the respective knee before the cuts are carried out bymeans of cutting tools in particular provided in the form of saws.

[0042] The starting point for the part of the total operation which canbe carried out by means of the set of instruments in accordance with theinvention is a base element 15 which is also termed a cutting block inthe following and which is fixed to the tibia 13 by means of holdingpins 16. The base element 15 has previously been positioned relative tothe tibia 13 such that the planar upper side of the base element 15 liesat the height of the tibial plateau to be produced in accordance withthe surgical plan by the position of the bone cuts to be Fixed. In otherwords: the upper side of the cutting block 15 sets the position andorientation of that cutting plane relative to the tibia 13 which is alsotermed the first cutting plane in the following.

[0043] However, the cutting depth with which this first bone cut has tobe carried out in the direction lateral-medial is thus not yet known tothe surgeon. It is likewise not known to the surgeon how the second bonecut inwardly bounding the tibial plateau should be orientated relativeto the tibia and thus to the first cutting plane. Both the optimum depthof the first cut in the direction of the cruciate ligaments and of theeminentia and the optimum orientation of the second cut along thecruciate ligaments and along the eminentia depend on the respective kneeanatomy and previously had to be fixed by the surgeon during theoperation without any aids and thus only “by feel”.

[0044] This is where the invention comes in. First, a cutting jig 11 ispushed onto the cutting block 15 with a U-shaped base part. The basepart includes an upper U limb 49 and a lower U limb 51. The lower U limb51 of the cutting jig 11 is guided in a groove, for example a T-shapedgroove, formed at the lower side of the cutting block 15 such that thecutting jig 11 can only be moved in the plane fixed by the upper side ofthe cutting block 15 and parallel to the guide groove of the cuttingblock 15, i.e. parallel to the U limbs 49, 51 relative to the cuttingblock 15.

[0045] The cutting jig 11 defines a first cutting plane for a first bonecut by means of a slot-shaped intermediate space 17 between the upper Ulimb 49 and the upper side of the base element 15. In this process, theslot 17 serves as a guide for the cutting tool provided as a saw bladein order to carry out this horizontal cut.

[0046] A second slot 19 extending perpendicular to the first slot 17 isformed in a turntable arrangement 37 of the cutting jig 11. Theturntable arrangement 37 permits the orientation of the second slot 19to be set relative to the cutting plane defined by the first slot 17.

[0047] A threaded spindle 45 provided with a handle 46 permits theturntable arrangement 37 to be fixed in the respectively set orientationand the cutting jig 11 to be simultaneously fixed to the base element15. This fixing of the cutting jig 11 and of the turntable arrangement37 takes place when the optimum orientation of the cutting plane fixedby the second slot 19 has been found.

[0048] To find the optimum orientation of the second vertical cuttingplane, a probe device 81 is coupled to the cutting jig 11. The probedevice 81 has a base part 85 with a strip-shaped coupling section 93which is inserted into the slot 19 of the turntable arrangement 37 inorder to establish a compulsory coupling between the probe device 81 andthe slot 19 defining the second cutting plane. Consequently, the probedevice 81 can be rotated via the coupling section 93 of the base part 85as a whole relative to the cutting jig 11 and thus relative to the tibia13 about an axis extending perpendicular to the cutting plane defined bythe first slot 17.

[0049] A further degree of freedom of movement of the probe device 81 isprovided by a probe including an actuation section 87 and a probe arm 89which is longitudinally displaceably guided parallel to the firstcutting plane on two guide pins 91 connected to the base part 85. Theprobe 83 can be latched to one of the guide pins 91 in differentpositions which each correspond to a pre-determined implant size.

[0050] After pushing the cutting jig 11 onto the cutting block 15 andthe insertion of the coupling section 93 into the rotatable slot 19 ofthe cutting jig 11, the optimum orientation of the second cutting planefixed by the slot 19 can be probed by displacing the coupling section 93in the medio-lateral direction and by rotating the probe device 81relative to the cutting jig 11 and fixed by the handle. In a furtherstep, the correct size of the implant relative to the outer edge can bedetermined by the surgeon on the tibia by displacing the probe 83 alongthe guide pins 91 and by moving the probe device along the secondcutting plane. With an implant size determined in this manner, a finecorrection can still be carried out at any time by a short-term releaseand renewed tightening of the handle 46.

[0051] In this process, the surgeon can grip the actuation section 87 ofthe probe device 81 with the one hand and the handle 46 of the cuttingjig 11 with the other hand and thus bring the total arrangement ofcutting jig 11 and probe device 81 into a configuration taking theanatomical circumstances of the respective knee into optimum account inaccordance with the given degrees of freedom of movement.

[0052] The surgeon determines the optimum configuration by probing bymeans of the coupling section 93 and of the probe arm 89 and by a visualcheck of the position of the coupling section 93 and of the probe arm 89relative to the tibia 13. To facilitate the visual check, the free endof the probe arm 89 is curved in accordance with the outer lateralboundary of the later implants.

[0053] When the optimum configuration of the set of instruments inaccordance with the invention and thus the optimum orientation of thesecond cutting plane as well as the best suitable implant size has beenset, the turntable arrangement 37 provided with the slot 19 is fixedwith respect to the cutting jig 11 and the cutting jig 11 is fixed withrespect to the cutting block 15 by rotating the thread spindle via thehandle 46. The probe device 81 is then removed.

[0054] Subsequently —guided via a passage 29 likewise formed at theturntable arrangement 37 and aligned with the slot 19 (cf. FIG. 1)—abore is formed in the bone into which an abutment pin 31 guided in thepassage 29 is then inserted (cf. FIG. 3). The passage 29 serving as aguide both for the drilling tool and for the abutment pin 31 is orientedsuch that its central axis extends parallel to the imagined sectionalline between the first slot 17 and the second slot 19 and such that itslongitudinal section covers the prolongation of the slots 17, 19 ascompletely as possible. Consequently, the abutment pin 31 introducedinto the bone through the passage 29 serves as an abutment bounding boththe first cut and the second cut for the saw blades guided through theslots 21, 23 (cf. FIGS. 3 and 4).

[0055] After the insertion of the abutment pin 31 into the bone, first,in accordance with FIG. 3, the first cut is carried out by means of thesaw blade 21 guided through the first slot 17 and its depth is boundedby the abutment pin 31 in the direction of lateral-medial. Subsequently,in accordance with FIG. 4, a second cut extending perpendicular to thefirst cut is carried out by means of the saw blade 23 guided through thesecond slot 19 and its depth is likewise bounded by the abutment pin 31in the distal direction.

[0056]FIG. 5 shows the tibia plateau created by means of the set ofinstruments in accordance with the invention and bounded by cut surfaces25, 27 extending perpendicular to one another, with moreover theabutment pin 31 coinciding with the line of intersection of the two cutsurfaces 25, 27 being shown.

[0057] Subsequently, the abutment pin 31 is pulled out, the clamping ofthe cutting jig 11 at the cutting block 15 is canceled and the cuttingjig 11 is removed from the cutting block 15. The tibia 13 is thusprepared for the insertion of the tibia implant of the knee prosthesis,with the opposite femoral condyle, however, having been preparedpreviously, with this, however, not being looked at in detail.

[0058] In accordance with FIG. 6, the cutting jig 11 in accordance withthe invention includes the U-shaped base part 47 with the two U limbs49, 51 extending in parallel. The free end of the upper U limb 49supports the turntable arrangement 37 which includes a turntable 39rotatably supported at the upper U limb 49 and an upper guide section 41provided with the slot 19 and a lower guide section 43 provided with thepassage 29. The guide sections 41, 43 are rotatably fixedly connected tothe turntable 39. The passage 29 is aligned with the slot 19, i.e. thecentral axis of the passage 29 lies in the cutting plane defined by theslot 19.

[0059] A clamping lever 53 is pivotably supported on the base part 47via a pin 54 about an axis extending perpendicular to the two U limbs49, 51. The clamping lever 43 includes a clamping arm 57 and anactuation arm 55 which extend in parallel offset to one another. Theclamping arm 57 formed in the manner of a tongue extends in acorrespondingly shaped recess of the lower U limb 51 and can be pivotedinto the region between the two U limbs 49, 51 by pivoting of theclamping lever 53.

[0060] The clamping lever 53 furthermore includes a thread section 56which is provided with an internal thread and which cooperates with aclamping spindle 45 having a corresponding external spindle. The spindle45 extends in the one direction through a guide opening which is formedin a support and guide section 62 formed by the free end region of theactuation arm 55 of the clamping lever 53. The clamping spindle 45 isprovided at its free end with the handle 46. The clamping spindle 45extends in the opposite direction in the form of a pin-shaped clampingsection 44 whose free end (not shown) can be brought into clampingengagement with an outer rim region of the turntable arrangement 37 whenthe spindle 45 is rotated in the corresponding direction.

[0061] A pressure spring 51 is clamped between a support section 59fixedly connected to the spindle 45 and the support and guide section 62and holds the external thread of the spindle 45 and the internal threadof the threaded section 56 of the clamping lever 53 without clearance inevery position of the spindle 45.

[0062] By rotating the spindle 45, the free end of the clamping section44 of the spindle 45 is moved in the direction of the turntablearrangement 37 and finally into clamping engagement with the turntablearrangement 37, whereby the turntable arrangement 37 is fixed relativeto the base part 47.

[0063] As soon as the spindle 45 is prevented from further axialmovement by the turntable arrangement 37, a turning further of thespindle 45 results in an axial movement of the threaded section 56 ofthe clamping lever 53 away from the turntable arrangement 37 and thus ina pivoting of the clamping lever 53, which has the consequence that theclamping arm 57 of the clamping lever 53 moves in the direction of theupper U limb 49 of the base part 47 and thus into the intermediate spacebetween the two U limbs 49, 51.

[0064] As already explained above in connection with FIGS. 1 to 5, theactuation of the clamping device including the clamping spindle 45 andthe clamping lever 53 takes place with the cutting jig 11 pushed ontothe cutting block 15, i.e. the cutting block 15 is located in theintermediate space between the two U limbs 49, 51. A relatively smallpivot movement of the clamping lever 53 is therefore sufficient in orderto fix the cutting jig 11 at the cutting block 15 via the clamping arm57 coming into clamping engagement with the lower side of the closingblock 15.

[0065] The turntable arrangement 37 can thus be both fixed and releasedagain with respect to the base part 47 of the cutting jig 11 and thecutting jig 11 can be both fixed and released again with respect to thecutting block 15 simultaneously by actuation of the spindle 47 via thehandle 46.

[0066] In accordance with FIG. 7, the base part 85 of the probe device81 includes a support 86 with which the strip-shaped coupling section93, on the one hand, and the two guide pins 91 for the probe 83displaceable relative to the base part 85 along the guide pins 91, onthe other hand, are connected.

[0067] The probe 83 includes the probe arm 89 having the curved free end90 and extending parallel to the coupling section 93 as well as anactuation section 87 at which an actuation lever 95 is pivotablysupported via a pin 94. A latching nose 96 of the one lever arm of theactuation lever 95 is biased toward the one guide pin 91 by arestoration spring 97 acting on the other lever arm of the actuationlever 95 and supported at the actuation section 87 such that, with anappropriate relative position between the base part 95 and the probe 83,the latching nose 96 engages into recesses formed at this guide pin 91,whereby the relative position between the base part 85 and the probe 83is fixed. The positions of the latch recesses of the guide pin 91correspond to the sizes of tibia implants of an existing set ofimplants.

[0068] The surgeon holding the probe device 81 coupled to the cuttingjig 11 (cf.

[0069]FIG. 2) at the actuation section 87 can release the latching ofthe probe 93 at the guide pin 91 by actuating the lever 95 against therestoring force of the spring 97 and can set all pre-determined implantsizes at the probe device 81 by displacing the probe 83 along the guidepins 91 relative to the base part 85 and can in this manner determinethe best matched implant size for the knee while taking the anatomicalcircumstances of the respective knee into account.

[0070] The abutment pin 31 shown in FIG. 8 (cf. also FIGS. 3 to 5)includes a straight abutment section 30 with which the abutment pin 31is inserted through the passage 29 formed at the turntable arrangement37 of the cutting jig 11 into the bore previously formed in the bone aswell as a holding section 32 angled by 90° at which the surgeon can gripthe abutment pin 31 on the insertion into the bone and on the pullingout from the bone. The free end of the holding section 32 is providedwith a radial extension. The abutment pin consists of a hardened metalalloy so. that no wear occurs on the lateral bounding of the saw blades.It is angled so that it cannot be confused with customary straight pins.

[0071] Reference numeral list

[0072]11 cutting jig

[0073]12 femur

[0074]13 tibia

[0075]15 base element, cutting block

[0076]16 holding pin

[0077]17 first slot

[0078]19 second slot

[0079]21 first cutting tool, first saw blade

[0080]23 second cutting tool, second saw blade

[0081]25 first cutting plane, first cutting surface

[0082]27 second cutting plane, second cutting surface

[0083]29 guide, passage

[0084]30 abutment section

[0085]31 abutment element, abutment pin

[0086]32 holding section

[0087]33 intersection line of the cutting planes

[0088]37 turntable arrangement

[0089]39 turntable

[0090]41 guide section

[0091]43 guide section

[0092]44 clamping section

[0093]45 actuation member, clamping spindle

[0094]46 handle

[0095]47 base part

[0096]49 upper U limb

[0097]51 lower U limb

[0098]53 clamping lever

[0099]54 pin

[0100]55 actuation arm

[0101]56 threaded section

[0102]57 clamping arm

[0103]59 support section

[0104]61 spring

[0105]62 support and guide section

[0106]81 probe device

[0107]83 probe

[0108]85 base part

[0109]86 support

[0110]87 actuation section

[0111]89 probe arm

[0112]90 curved free end

[0113]91 guide pin

[0114]92 latch recess

[0115]93 coupling section

[0116]94 pin

[0117]95 actuation lever

[0118]96 latching nose

[0119]97 restoration spring

1. An apparatus for the fixing of the position of bone cuts for theinsertion of knee implants, comprising at least one cutting jig (11)which can be coupled to a base element (15) fixed to the bone in theregion of a condyle and can be fixed to the base element (15), whereinthe cutting jig (11) defines, in the fixed state and in each case bymeans of a slot (17, 19) for a cutting tool (21, 23), a first cuttingplane (25) with respect to the base element (15) and a second cuttingplane (27) with respect to the first cutting plane (25), and wherein theorientation of the second cutting plane (27) is adjustable relative tothe first cutting plane (25) when the cutting jig (11) is coupled to thebase element (15) and while taking the respective knee anatomy intoaccount.
 2. An apparatus in accordance with claim 1, wherein the firstcutting plane (25) and the second cutting plane (27) extendperpendicular to one another.
 3. An apparatus in accordance with claim1, wherein the orientation of the second cutting plane (27) isadjustable with the cutting jig (11) movable relative to the baseelement (15), with the cutting jig (11) being movable only parallel tothe first cutting plane (25) and only in a straight line.
 4. Anapparatus in accordance with claim 1, wherein the cutting jig (11) iscompulsorily guided at the base element (15) by a guide groove formed atthe base element (15).
 5. An apparatus in accordance with claim 1,wherein the cutting jig (11) has at least one guide (29) for an abutmentelement (31) which, in at least one of the cutting planes (25, 27),forms an abutment for the cutting tool (21, 23) restricting therespective cut.
 6. An apparatus in accordance with claim 5, wherein theguide (29) can be made such that the abutment element (31) lies on aline of intersection (33) of the two cutting planes (25, 27).
 7. Anapparatus in accordance with claim 5, wherein the guide (29) for theabutment element (31) is compulsorily coupled to the slot (19) definingthe second cutting plane (27).
 8. An apparatus in accordance with claim5, wherein the guide (29) includes a passage formed in the cutting jig(11) through which the abutment element (31) can be inserted.
 9. Anapparatus in accordance with claim 5, wherein the abutment element (31)is provided in the form of an abutment pin which can be introduced intothe bone (13) before the carrying out of the bone cuts.
 10. An apparatusin accordance with claim 1, wherein an adjustable probe device (81) isprovided to take the knee anatomy into account and can be compulsorilycoupled to the slot (19) of the cutting jig (11) defining the secondcutting plane (23), with it being possible to set a plurality ofpre-determined implant sizes by adjusting a probe (83) relative to abase part (85) coupled to that slot (19).
 11. An apparatus in accordancewith claim 1, wherein the slot (17) defining the first cutting plane(25) is formed by an intermediate space present between the upper sideof the base element (15) and a side of the cutting jig (11) facing thebase element (15) when the cutting jig (11) is coupled to the baseelement (15).
 12. An apparatus in accordance with claim 1, wherein thecutting jig (11) includes a turntable arrangement (37) with a turntable(39) which is rotatably supported at the cutting jig (11) and with whicha guide section (41) is rotatably fixedly connected in which the slot(19) defining the second cutting plane (27) is formed, wherein therotational axis of the turntable (39) preferably extends perpendicularto the first cutting plane (21).
 13. An apparatus in accordance withclaim 12, wherein a further guide section (43) is rotatably fixedlyconnected to the turntable (39) and is formed as a guide (29) for theabutment element (31).
 14. An apparatus in accordance with claim 1,wherein the cutting jig (11) furthermore has a clamping device with anactuating member (45) by means of which the cutting jig (11) can befixed relative to the base element (15) and simultaneously theorientation of the second cutting plane (27) can be fixed relative tothe first cutting plane (25).
 15. An apparatus in accordance with claim1, wherein the cutting jig (11) includes a U-shaped base part (47) whichcan be pushed onto the base element (15) and having U-limbs (49, 51)extending parallel to the first cutting plane (25), a clamping lever(53) pivotably supported at the base part (47) about an axis extendingparallel to the first cutting plane (25) and perpendicular to the Ulimbs (49, 51) of the base part (47) and a clamping spindle (45)extending parallel to the U limbs (49, 51) of the base part (47) andcooperating with the clamping lever (53) via a thread, wherein aturntable arrangement (37) rotatably supported at the upper U limb (49)of the base part (47) about an axis extending perpendicular to the firstcutting plane (25) and having the slot (19) defining the second cuttingplane (27) capable of being fixed by a rotational actuation of theclamping spindle (45) and simultaneously the clamping lever (53) beingpivotable relative to the base part (47) into clamping engagement withthe base element (15).
 16. An apparatus in accordance with claim 15,wherein a free end region of the clamping spindle (45) is made for thefixing of the turntable arrangement (37) and can be brought intoclamping engagement with an outer rim region of the turntablearrangement (37) by the rotational actuation of the clamping spindle(45).
 17. An apparatus in accordance with claim 15, wherein the clampinglever (53) includes an actuation arm (55) and a clamping arm (57), withthe clamping spindle (45) cooperating with the actuating arm (55) andthe clamping arm (57) being pivotable, for the clamping tight of thebase element (15) located between the two U limbs (49, 51) of the basepart (47), by rotational actuation of the clamping spindle (45) via theactuating arm (55) into a region between the two U limbs (49,51) andtoward the base element (15).
 18. An apparatus in accordance with claim15, wherein cooperating threaded sections of the clamping spindle (45)and of the clamping lever (53) are held free of clearance by a spring(61) clamped between a contact section (59) fixed with respect to thespindle and the actuation arm (55) of the clamping lever (53).
 19. Anapparatus in accordance with claim 15, wherein an intermediate spacebetween the two U limbs (49, 51) of the base part (47) is matched to theheight of the base element (15) and is designed for a base element (15)with a height of approximately 12 mm.